Spacecraft require a large number of devices for maintaining a desired orbit while performing their intended function. These devices are located in the payload area and throughout a spacecraft and may include electronic, electrical, electromechanical and ferrite devices. Command of these devices is vital to a successful mission.
Conventional control methods utilize a central command unit. This central command unit delivers numerous low current signals, each on a separate wire, to the many remotely located electronic devices. There are several disadvantages to this method. For example, this method requires the use of large, heavy and expensive wire harnesses. Furthermore, the size, weight and cost of these wire harnesses significantly restrict the possible layout or arrangement of electronic devices in the payload area. Additionally, conventional control methods have limited command capabilities.
Many spacecraft have extremely tight requirements on the weight of various spacecraft components. Reducing component weight has many attendant advantages. For example, the requirements for structural integrity and the amount of fuel required to launch a spacecraft are related to the weight of the spacecraft. Similarly, control and maintenance of an appropriate orbit may also be affected by the weight of the spacecraft.
Electrical energy used to control spacecraft and power communication equipment is often provided initially by one or more batteries and then supplemented by solar energy collected by large solar panels deployed once in orbit. Spacecraft power consumption must be carefully monitored and controlled to provide consistent, high quality communication during a mission. Power requirements also indirectly affect the weight of the spacecraft due to the necessary energy storage capacity of the batteries so that sufficient energy may be provided during periods when solar energy is reduced or unavailable.
Thus, component weight and power consumption are two important parameters of the many considerations during design and implementation of any spacecraft. It is desirable to reduce or minimize both component weight and power consumption to improve the efficiency and reduce the cost of construction and/or operation of the spacecraft based on its intended mission.